A vehicle such as a truck is generally equipped with one or several differential units on its driven axles.
Typically, such an axle comprises a differential carrier housing which contains a differential and two drive shafts each having one end connected to the differential and a second end connected to a wheel of the vehicle via a wheel hub. Furthermore, a cover is mounted at each end portion of the axle. A stop is provided between the cover and the facing end of the drive shaft, in order to limit the movement of the drive shaft along the axle axis, and to ensure proper operation of the axle.
Such stops are under significant constraints:                in use, and in particular during gearshifts, a drive shaft can move along the axle axis towards the corresponding wheel, which causes shocks on the cover and can ultimately result in the cover breakage;        as the stop is fastened to the cover and in contact with the drive shaft end face, which rotates with respect to the cover, the stop is subjected to high friction efforts. This leads to premature wear, unless expensive specific treatments of the pieces or expensive specific intermediate components (such as a ball bearing) are provided.        
Therefore, many stops of the prior art have a fairly low durability, which requires maintenance.
Another weakness of the stops of the prior art is that they require complex adjustments during production to provide an appropriate clearance between the drive shaft end face and the stop arranged on the cover.